1. Field of the Invention
The present invention relates to crash survivable enclosures for flight recorders used in aircraft and other vehicles operating over land and water. More particularly, the invention is directed toward a crash survivable enclosure which is capable of withstanding high impact, shock and mechanical penetration forces that commonly occur in a crash and the high temperatures, flames and heat that often develop after a crash. In addition, the enclosure is specially designed for resisting damage to solid state memory devices contained therein, even if the enclosure subjected to immersion in fresh water or salt water to a depth of up to 20,000 feet for a prolonged period of thirty days or more.
2. Description of the Prior Art
Solid state memory devices have been used in flight recorders for recording essential flight data or information useful in determining causes of crashes or other mishaps in aircraft and other vehicles. When a crash occurs, it is essential that the recorded information on board survive the crash and subsequent events including heat, cold, flame and fire that may afterwards ensue. In addition, should the crash or impact occur over the ocean or another body of water, it is essential that the crash survivable portion of the flight data recorder remain intact for a prolonged period of time, even though the enclosure is submerged to a substantial depth in sea water or fresh water until the recorder is eventually located and retrieved for examination of the data contained in the solid state memory devices thereof.
U.S. Pat. No. 2,328,208 discloses an ejectable package containing a device for recording information and indicating location of a fallen airplane. The ejectable package includes a container for a recording instrument, a parachute and a smoke bomb which is activated to signal the aircraft location after a crash and the container is designed to float upon a body of water.
U.S. Pat. No. 2,959,671 discloses a crash position indicator which forms part of the aerodynamic surface of a rear portion of an aircraft and which contains a radio beacon mounted in a tumbling airfoil shape which is separated from the aircraft fuselage and is shaped to minimize damage and preserve recorded information contained therein.
U.S. Pat. No. 3,140,847 discloses an ejectable flight recorder including a capsule and means for ejecting the capsule automatically with a parachute automatically being employed to slow the descent of the ejected capsule to minimize damage thereto. The capsule can be automatically ejected with explosive force after an aerospace vehicle has hit the ground.
U.S. Pat. No. 3,181,809 discloses an aircraft crash recording unit housed within a canister which is ejected from the aircraft and includes a parachute and a flotation bag for preventing the canister from sinking in the water.
U.S. Pat. No. 3,583,657 discloses an apparatus for the underwater ejection of a buoyant aircraft flight recorder in a crash proof container. The apparatus operates in response to a pressure sensor and allows the crash protected enclosure to escape from a water immersion depth of 25 to 35 feet to move upwardly and float on the surface.
U.S. Pat. No. 3,978,410 discloses an aircraft mounted crash activated transmitter device which is automatically ejected from the aircraft and which includes a foam filled outer circular case which is designed to withstand certain "G" loading.
U.S. Pat. No. 4,694,119 discloses a heat shielded memory unit for an aircraft flight data recorder employing thermal insulation to prevent the loss of data if the aircraft burns.